Microsoft's browsers last month continued to swirl toward the drain of second place, new data published last week showed.

The several editions of Internet Explorer (IE) and Edge lost a combined 1.4 percentage points of desktop and notebook user share in March, the fourth consecutive monthly decline of more than a point and the 15th straight month of declines of any size.

IE and Edge -- analytics company Net Applications dumps the latter's user share into the bucket labeled "IE" -- accounted for 43.4% of all browsers used to reach the Web last month. A year ago, that number was 56.5%.

Unless the slide suddenly slows -- and there was only a hint that it would -- Microsoft's browsers will drop into second place in May. There is an outside chance that Microsoft will lose its No. 1 spot in Net Applications' browser rankings this month.

It's possible that IE will stem the bleeding: March's losses were the smallest in four months. But the synchronized climb in Google Chrome's user share -- Net Applications' estimate of the percentage of users worldwide who used the browser to go online -- signaled that the decline of IE will not be halted anytime soon.

Chrome boosted its user share by 2.5 percentage points last month, absorbing all the losses of both IE and Mozilla's Firefox, and is poised to replace Microsoft's browsers as the world's most-used. Chrome ended March with a user share of 39.1%, 14.1 points higher than 12 months earlier.

Firefox also lost ground in March, dropping 1.1 percentage points to 10.5%, its largest one-month decline since December 2014. Firefox is staring at at single-digit user share as early as May.

Apple's Safari and Opera Software's Opera were flat last month at 4.9% and 1.7%, respectively.

About one-third of all IE users ran an unsupported version last month, and so did not receive the usual security updates Microsoft released March 8.

By forcing customers to upgrade to a newer version of IE -- or alternately, turn to Windows 10 and its default Edge -- Microsoft demanded that users change browsers. That had a disastrous impact on IE's user share as people rethought their browser choice, and then abandoned Microsoft's browsers for rivals' -- notably Chrome.

Firefox's problems have been different: Mozilla's flagship has been in slow decline for more than five years. The browser that once shook up the market -- it was the first to take on IE, and triggered a resumption of browser development by Microsoft -- has gradually slipped toward irrelevance.

Apple's Safari, although with less than half the user share of Firefox, seems relatively secure because of its ties to OS X, the operating system that powers Macs. About two-thirds of those running OS X used Safari to reach the web in March, consistent with a long-established trend.

IE and Edge, meanwhile, were the preferred browsers of just 48% of Windows users, a record low and the second straight month of sub-50% penetration in that critical arena. The fact that even fewer Windows 10 customers ran Edge -- 30.4% -- boded ill for Microsoft's attempt to hold the overall No. 1 browser spot as more people upgraded to the new OS.

Not surprisingly, Microsoft's share of mobile browsers was substantially less than on personal computers. On mobile, Microsoft's March share was just 2.5%, a minuscule fraction compared to Google's 55.7% and Apple's 32.7%.

Net Applications

Microsoft and Google will swap spots as the No. 1 and No. 2 browser makers in May if the trends established over both the last 3 and 12 months continue.